checkstyle Preparation for Migration of Checkstyle Codebase to Java 17

Currently, Checkstyle is using JDK 11 as the baseline version. However, Java has evolved significantly, and most of the ecosystem has now moved towards JDK 21.

This issue proposes to incrementally upgrade Checkstyle’s baseline JDK version in two stages:

move all Inputs for JDK 12-17 to compiled folder
update all CIs to use jdk17, there should be no jdk11 be left. Still not updates in pom.xml for required jdk.
send PR to upgrade pom.xml to min required jdk, to see CI and make further plan.
update pom.xml - it should be separate issue as it is big breaking change and it would be visible in release notes clearly. Version will be 11.0.0
revert changes in pom.xml to make Inputs be compiled by maven.
review all PRs with dependencies and prepare them for merge, may be just rebase in UI will be required.

Jun 04 '25 17:06 AmitKumarDeoghoria

Doing all at one will be too challenging.

Please send PR to move all non completable Inputs from jdk less or equal to jdk17 to compiled folder and update CI to do not have jdk11 compile for inputs

Jun 05 '25 01:06 romani

Doing all at one will be too challenging.

Please send PR to move all non completable Inputs from jdk less or equal to jdk17 to compiled folder and update CI to do not have jdk11 compile for inputs

Made these changes in the PR #17169. Now as a next step will resolve all test failures as a result of moving all these files

Jun 05 '25 19:06 AmitKumarDeoghoria

I put misc label, because for now we do not break compatibility. upgrade of pom.xml will be breaking changes and we bump version to 11.0.0

Jun 08 '25 14:06 romani

All further updates should be in scope of https://github.com/checkstyle/checkstyle/issues/17321

Jul 08 '25 19:07 romani